An Associated Press survey of the state's five superdelegates found that they all plan to back the former U.S. secretary of state at the party's national convention next year. She's running against U.S. Sen. Bernie Sanders of Vermont and former Maryland Gov. Martin O'Malley for the nomination.

Superdelegates are Democratic National Convention delegates who can support the candidate of their choice, regardless of what happens in primaries and caucuses. They are members of Congress and other elected officials, party leaders and Democratic National Committee members.

Clinton won Arkansas' primary in her unsuccessful 2008 White House bid. Republicans hold all of the state's congressional seats.

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